Conventionally, there is known a speaker apparatus in which a plurality of ultrasonic vibrators is arranged in array to provide the directivity. This speaker apparatus is also called a parametric speaker, and applies, to the plurality of ultrasonic vibrators, the voltage of an ultrasonic wave modulated by a sound signal of an audible frequency band to be able to generate an audible sound in a specific direction (see Japanese Laid-open Patent Publication No. 2011-010224, for example).
However, the conventional speaker apparatus has a configuration in which a large number of ultrasonic vibrators are arranged in array in order to exert the directivity, and thus there exists a problem that miniaturization of a vibration part is difficult.